81561481495481 has 16 divisors (see below), whose sum is σ = 87940310008320. Its totient is φ = 75197687731200.

The previous prime is 81561481495433. The next prime is 81561481495513. The reversal of 81561481495481 is 18459418416518.

It is a cyclic number.

It is not a de Polignac number, because 81561481495481 - 2¹⁴ = 81561481479097 is a prime.

It is a super-2 number, since 2×81561481495481² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81561481495981) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 35496146 + ... + 37723988.

It is an arithmetic number, because the mean of its divisors is an integer number (5496269375520).

Almost surely, 2^{81561481495481} is an apocalyptic number.

It is an amenable number.

81561481495481 is a deficient number, since it is larger than the sum of its proper divisors (6378828512839).

81561481495481 is a wasteful number, since it uses less digits than its factorization.

81561481495481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2231216.

The product of its digits is 44236800, while the sum is 65.

The spelling of 81561481495481 in words is "eighty-one trillion, five hundred sixty-one billion, four hundred eighty-one million, four hundred ninety-five thousand, four hundred eighty-one".